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Aircraft_design.pdf
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Symbols and Abbreviations

Symbols

A

area

A1

intake highlight area

Ath

throat area

APR

augmented power rating

AR

aspect ratio

AW

wetted area

a

speed of sound; acceleration

average acceleration at 0.7 V2

ac

aerodynamic center

B

breadth, width

b

span

CR, CB

root chord

CD

drag coefficient

CDi

induced drag coefficient

CDp

parasitic drag coefficient

CDpmin

minimum parasitic drag coefficient

CDw

wave drag coefficient

Cv

specific heat at constant volume

CF

overall skin friction coefficient; force coefficient

Cf

local skin friction coefficient; coefficient of friction

CL

lift coefficient

Cl

sectional lift coefficient; rolling moment coefficient

CLi

integrated design lift coefficient

CLα

lift curve slope

CLβ

sideslip curve slope

Cm

pitching-moment coefficient

Cn

yawing-moment coefficient

Cp

pressure coefficient; power coefficient; specific heat at constant

 

pressure

CT

thrust coefficient

CHT

horizontal tail volume coefficient

xxi

xxii

Symbols and Abbreviations

CVT

vertical tail volume coefficient

Cxxxx

cost, with subscript identifying parts assembly

C xxxx

cost, heading for the type

CC

combustion chamber

CG

center of gravity

c

chord

croot

root chord

ctip

tip chord

cp

center of pressure

D

drag; diameter

Dskin

skin friction drag

Dpress

pressure drag

d

diameter

E

modulus of elasticity

e

Oswald’s factor

F

force

f

flat-plate equivalent of drag; wing span

fc

ratio of speed of sound (altitude to sea level)

Fca

aft-fuselage closure angle

Fcf

front-fuselage closure angle

FB

body axis

FI

inertia axis

FW

wind axis

Fxxx

component mass fraction; subscript identifies the item (see Sec-

 

tion 8.8)

F/ma

specific thrust

FR

fineness ratio

g

acceleration due to gravity

H

height

h

vertical distance; height

J

advance ratio

k

constant (sometimes with subscript for each application)

L

length; lift

LFB

nacelle forebody length

LHT

horizontal tail arm

LN

nacelle length

LVT

vertical tail arm

L

length

M

mass; moment

Mf

fuel mass

Mi

component group mass; subscript identifies the item (see Sec-

 

tion 8.6)

Mxxx

component item mass; subscript identifies the item (see Sec-

 

tion 8.6)

m˙ a

airmass flow rate

m˙ f

fuel mass flow rate

Symbols and Abbreviations

xxiii

m˙ p

primary (hot) airmass flow rate (turbofan)

 

m˙ s

secondary (cold) airmass flow rate (turbofan)

 

N

revolutions per minute; number of blades; normal force

 

Ne

number of engines

 

n

load factor

 

ng

load factor × acceleration due to gravity

 

P, p

static pressure; angular velocity about X-axis

 

pe

exit plane static pressure

 

p

atmospheric (ambient) pressure

 

Pt, pt

total pressure

 

Q

heat energy of the system

 

q

dynamic head; heat energy per unit mass; angular velocity about

 

 

Y-axis

 

R

gas constant; reaction

 

Re

Reynolds number

 

Recrit

critical Reynolds number

 

r

radius; angular velocity about X-axis

 

S

area (usually with the subscript identifying the component)

 

SH

horizontal tail reference area

 

Sn

maximum cross-sectional area

 

SW

wing reference area

 

SV

vertical tail reference area

 

sfc

specific fuel consumption

 

T

temperature; thrust; time

 

TC

nondimensional thrust

 

TF

nondimensional force (for torque)

 

TSLS

sea-level static thrust at takeoff rating

 

T/W

thrust loading

 

t/c

thickness-to-chord ratio

 

tf

turbofan

 

Ug

vertical gust velocity

 

U

freestream velocity

 

u

local velocity along X-axis

 

V

freestream velocity

 

VA

aircraft stall speed at limit load

 

VB

aircraft speed at upward gust

 

VC

aircraft maximum design speed

 

VD

aircraft maximum dive speed

 

VS

aircraft stall speed

 

Ve

exit plane velocity (turbofan)

 

Vep

primary (hot) exit plane velocity (turbofan)

 

Ves

secondary (cold) exit plane velocity (turbofan)

 

W

weight; width

 

WA

useful work done on aircraft

 

WE

mechanical work produced by engine

 

W/Sw

wing; loading

 

xxiv

Symbols and Abbreviations

X

distance along X-axis

y

distance along Y-axis

z

vertical distance

Greek Symbols

α

angle of attack

β

CG angle with vertical at main wheel; blade pitch angle; sideslip

 

angle

 

dihedral angle; circulation

γ

ratio of specific heat; fuselage clearance angle

 

increment measure

δ

deflection

ε

downwash angle

ηt

thermal efficiency

ηp

propulsive efficiency

ηo

overall efficiency

θ

angle

 

wing sweep (subscript indicates the chord line)

λ

taper ratio

µ

friction coefficient; wing mass

 

summation

ρ

density

θ

fuselage upsweep angle

π

pi

σ

atmospheric density ratio

τ

thickness parameter

ω

angular velocity

Subscripts

(In many cases, subscripts are spelled out and are not listed here.)

a

aft

ave

average

ep

primary exit plane

es

secondary exit plane

f

front; fuselage

fb

blockage factor for drag

fh

drag factor for nacelle profile drag (propeller-driven)

fus

fuselage

HT

horizontal tail

M

middle

N, nac

nacelle

o

freestream condition

p

primary (hot) flow

s

stall; secondary (cold) flow

t, tot

total

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